98 Ram 318 (5.2L), manual trans, 140K miles. the first time I start it, it cranks longer than normal and is had to start and it doesn't sound like a normal start. After I drive it and stop and shut her down, she starts right up. Any thoughts on this baffling issue. I even put in new plugs, cap and rotor thinking that might help but it made no difference. Need ideas on what to fix. Thx.

 

Mine does the same thing sounds like its idling really ruff i noticed it takes a few seconds for the oil pressure to go up then idles fine. Not sure what the problem is after that first start it starts up fine until the next day

 

What that is may be your IAC motor that is stuck upon start thus not allowing air into the TB which causes a rich fuel mixture and low idle upon start. Once it's warmed up, the piston stays seated in the open position and allows air into the TB for quick start ups. It's supposed to start up on one click.

The other thing associated with that same component is rough idle condition.

On the other hand, it also could be a leaking fuel injector / leaky fuel supply or low fuel pressure present upon start up.

Either the fuel is draining back down into the tank due to a leak in the fuel system someplace or, there's a damaged or worn o-ring that is allowing air into the system thus causing the fuel to drain back down into the tank.

I had the first issue, bad IAC motor. It was a cheap one with an exposed spring that didn't work even new. I replaced it with a better one and solved my start up problems.

 

Great thought. Thx. where do I find the IAC motor on the engine, and where should I buy a replacement? BTW, the idle is not really rough, but it's at 500rpm which seems low to me.

 

The IAC in mounted on the back of the throttle body.

 

thanks. a friend of mine thought the issue could be a bad coolant temp sensor giving bad readings to the pcm at start-up. what does the forum think? could there be others issues?

 

Sure, lots of things can cause low idle and hard start as I too had an issue with this week. In my case, it was the IAC motor which was not moving the piston and, when first started it was very low in RPMs. In your case, you have a 500 rpm idle speed which is the same thing that I had. In that case the IAC is most likely suspect.

When, you replace it, just lightly grease the o-ring so that it's just shiny. It will seal better and you won't damage the seal when installing it.

NOTE: Get a good IAC and, by that let me explain what I mean.

Some have an open end where, the spring and piston are exposed. Those are problematic and I have been through many of those over the years. The one you want to use is the one that has a plastic sleeving over the spring thus preventing carbon build-up from building up on the shaft. They last a lot longer and work far better than the open face models.

Now, the coolant temp sensor is not going to lower your idle. I have ten bucks on the IAC.

Is this issue only when idling or starting for the first time? Is it sporadic or constant?

If it is while driving that it is always low:

If the TPS - throttle position sensor goes bad, that affects the engine rmps while driving and if it's bad enough, it will cause engine loping while driving but, not at idle.

Again, my bet is on the IAC or, a VAC issue. A vacuum issue will also create a low rpm condition and or rough idle. Clean your PCV and the hose. If it hasn't been replaced in years- get a new one. Reason being that the spring eventually collapses and no longer has any spring. Also check your oil breather element on the other valve cover. If it's plugged with oil it needs to be replaced to allow proper flow.

Start there with those since they are the most simple causes of idle and hard start conditions.

Oh, one more thing- if your TB has never been cleaned, it should be removed and thoroughly cleaned of all carbon deposits. If the IAC passages are blocked- it will not run / start very well nor idle right. If the bores are dirty and gummed up with varnish, same thing- it will not run good. I went through this with my OEM TB years ago. I went through 3 IACs before taking it off to find what the root problem really was.

PS: Replace your ASD (automatic shut down) relay as this is also can cause issues with starting and idle conditions. It is in the fuse box next to the battery. It is labeled to show where the ASD relay is. Just disconnect the battery before removing and installing the new one.

Good luck.

 

if the idle is fine then it may not be the iac. get a haynes manual and test the iac using the diagnostic procedures in it.

read this: https://dodgeforum.com/forum/2nd-gen...-starting.html

 

the main issue is hard start the first thing in the am. The idle is low (500 rpm) whether cold or hot and seems constant. there's no rough idle other than an occasional roughness which i attribute to the mileage and likely excessive carbon build-up arising from a most likely blown plenem gasket. Note, i have been using premium gas 91 octane for the past 7 years along with a 180 degree thermostat to prevent pinging.

 

thanks. great advice. the main issue is hard start the first thing in the am. The idle is low (500 rpm) whether cold or hot and seems constant. there's no rough idle other than an occasional roughness which i attribute to the mileage and likely excessive carbon build-up arising from a most likely blown plenem gasket. Note, i have been using premium gas 91 octane for the past 7 years along with a 180 degree thermostat to prevent pinging.